Process for refining mineral oil



May 22, 1934. A, FLOWERS 1,959,712

PROCESS FOR REFINING MINERAL OIL Filed Aug. 8,- 1930 patented May Z22, 1934 iil ii'iED STATES rnoonss FOR REFINING MINERAL OIL.

Alan E. Flowers, houghkeepsie, N. Y assignor to The De Laval Separator Company, New York, N. Y., a corporation of New Jersey Application August 8,

Claims.-

My invention relates to those processes for refining mineral oils, and particularly lubricating oils, which involve treatment with mineral acid, usually sulfuric acid.

The objects of the invention are to shorten the time required for acid treatment, to facilitate separation of the acid sludge, to avoid the necescity of subsequent neutralization with caustic soda or other alkali, and to improve the quality of the product.

In the refinement of oils, particularly lubricating oils, it is old to mix the oil with sulfuric acid, and, by air blowing, or by mechanical means, cause intimate contact of the oil and acid, and to thereafter allow the resultant tar, known as acid sludge, to settle out by gravity. This settling normally requires from to hours, and even then there is left in the oil a considerable quantity of sludge in the form of fine particles, known as pepper sludge, which has to be washed out by water and the final traces of which must be neutralized by alkalies.

In the past many attempts have been made to centrifugally separate out this pepper sludge, but none of them have met with success.

I have found that by using a particular process of mixing, hereinafter described, it is possible, in from 5 to minutes, to complete the reaction between the acid and the oil and put the resultant 30 sludge into a condition capable of complete, or

substantially complete, separation by centrifugal means, thereby eliminating the need of subsequent caustic treatment.

The process is not dependent for its execution on the employment of any particular apparatus.

However, the mixer shown in the accompanying drawing has been found to be well adapted to a highly efficient practice of the process. Fig. l

is a view of the mixer partly in side elevation and 4c partly with the shell cut away to show the interior construction; Fig. 2 is a cross-section through the shell.

A cylindrical casing a is provided at both ends with heads h each having a bearing 0 in the center thereof. Through these bearings extends a shaft (1 provided at one end with a pulley c for rotating the shaft. Within the mixer there are strung on and attached to the shaft d mixing blades 1 set at an angle of not less than to a plane nonnalto the center line of the shaft and having their ends in close proximity to the shell a. g is an inlet to, and h an outlet from, the mixer. The mixer is preferably set with a slight slope from the inlet end to the outlet end.

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The blades are attached to the shaft at points 1930, Serial No. 473,864

arranged along two lines extending hell-sally around the shaft. The blades are so positioned that they occupy overlapping zones, so that there are no quiescent spaces, affording short circuits, in the cylindrical liquid body.

In operation oil and acid are fed simultaneously from tanks and through-flow regulating devices (not shown) into the pipe 9 and thence into the mixer, wherein the blades 1, moving at a peripheral speed of not less than 2 nor more than 10, preferably about 4, feet per second, effect intimate contact between, and mixture of, the oil and the acid. The peripheral speed of the blades is of importance, since a lower speed than the prescribed minimum is found not to give ef- 7 ficient mixing, while a higher speed than the prescribed maximum causes the sludge to be broken into such small particles that its subsequent separation from the oil is difiicult. The feed is maintained at a rate to cause the oil to flow through the mixing tank in a time depending on the character of the oil, but not less than 5, and usually not more than 20, minutes. The mixture is taken directly from the outlet into a high speed centrifugal separator, wherein, because of the condition of the acid sludge as well as difference in specific gravity, the oil and sludge are separated, being continuously discharged therefrom in different streams.

I have found that the above described device will do sufiicient mixing to cause complete reaction and yet will avoid the whipping that breaks the reaction products up into such fine, particles that they cannot be separated out.

Although no precise temperature for mixing and separation is required, I have found that the best results are obtained at temperatures below 60 C.; for example, 50 C. Temperatures above 60 C. are usually undesirable.

What I claim is:

1. The process of refining mineral oil which comprises continuously feeding oil and acid in a substantially constant and predetermined ratio into one end of a cylindrical shaped body of oil and acid, subjecting the liquid body to a multitude of continuous mechanical pushing actions operative in a combined circumferential and longitudinal direction throughout overlapping zones of the liquid body, thereby causing the particles of the liquid body to progress therethrough in a substantially spiral course, predetermining the force and speed of the pushing actions to effect a traverse of the particles to the other end of the cylindrical liquid body in from five to twenty minutes, and continuously discharging the mix- 110 ture of oil and acid sludge from the other end of the cylindrical liquid body.

2. The process of refining mineral oil which comprises continuously feeding oil and acid in a substantially constant and predetermined ratio into one end of a cylindrical shaped body of oil and acid, subjecting the liquid body to a multitude of continuous mechanical pushing actions operative in a combined circumferential and longitudinal direction continuously upon approximately the Whole liquid body, thereby causing the particles of the liquid body to progress therethrough in a substantially spiral course, predetermining the force and speed of the pushing actions to effect a traverse of the particles to the other end of the cylindrical liquid body in from five to twenty minutes, and continuously discharging the mixture of oil and acid sludge from the other end of the cylindrical liquid body and immediately centrifugally separating the acid sludge from the oil.

3. The process of refining mineral oil which comprises feeding oil and acid in a substantially constant and predetermined ratio into one end of a cylindrical body of oil and acid, mechanically pushing the liquid in a circumferential direction throughout a multitude of overlapping zones, said pushing action operating at the peripheral part of the liquid body at a speed between 2 and 10 feet per second, simultaneously mechanically pushing the liquid in a longitudinal direction away from the point of feed, and continuously discharging the mixture 'of oil and acid sludge from the other end of the cylindrical body of liquid.

4. The process of refining mineral oil which comprises feeding oil and acid in a substantially constant and predetermined ratio into one end of a cylindrical body of oil and acid, mechanically pushing the liquid in a circumferential direction throughout a multitude of overlapping zones, said pushing action operating at the peripheral part of the liquid body at a speed between 2%; and 10 feet per second, simultaneously mechanically pushing the liquid in a longitudinal direction away from the point of feed, and continuously discharging the mixture of oil and acid sludge from the other end of the cylindrical body of liquid and immediately centrifugally separating the acid sudge from the oil.

5. The process of refining mineral oil which comprises feeding oil and acid in a substantially constant and predetermined ratio into one end of a cylindrical body of oil and acid, subjecting the liquid of said body to a multitude of mechanical pushing actions operating in longitudinal and circumferential directions throughout a multitude of overlapping zones, the pushing action operating at the peripheral part of the liquid body at a speed between two and one-half and ten feet per second, the resultant of the pushing forces effecting a more rapid displacement of the mixture circumferentially than longitudinally, the pushing force and the diameter and length of the cylindrical liquid body being such as to effect a traverse of the particles from one end to the other in between 5 and 30 minutes, continuously discharging the mixture of oil and acid sludge from the other end of the cylindrical body of liquid, and immediately centrifugally separating the acid sludge from the oil.

ALAN E. FLOWERS. 

